| 摘要 |
PURPOSE:To perform sure discrimination, by switching the 1st phase comparison via a loop gain switching circuit through the magnitude of an output of a rectifying circuit and also switching a phase locked loop conversion gain connected to one of a loop filter. CONSTITUTION:In a circuit system where switching control is done for a conversion gain determined with a phase comparator 27 and a loop filter 28 via a loop gain switching circuit 30 from a connecting point between a rectifying circuit 23 and a Schimtt circuit 25', a pilot signal and an output phase-shifting by 90 deg. an output of a voltage controlled oscillator 29 via a shaping circuit 20 and a 90 deg. phase shifter 21 are synchronizingly detected at a phase comparator 22, and when the pilot signal is inputted, a loop gain circuit 30 is made operative with a DC output from the rectifying circuit 23 to decrease the conversion gain determined with the phase comparator 27 and a loop filter 28, allowing to lower the overall loop gain of a PLL. If no pilot signal is inputted, the switching circuit 30 is not operated. |
